Gunnel Bjerneroth

Propofol induces a lowering of free cytosolic calcium in myocardial cells.

Background: The intravenous anaesthetic drug propofol has been shown to depress myocardial contractility. Ketamine, on the other hand, is a well‐documented cardiovascular stimulant. These differences could possibly be due to different effects of the drugs on the calcium homeostasis of the myocardium. Methods: The fluorescent intracellular probe fura‐2 acetoxyme‐thy1 ester (fura‐2/AM) was used in this in vitro investigation to study the influence of intravenous anaesthetic drugs on free cytosolic calcium concentration in suspensions of isolated rat myocardial cells.

Expression and function of a CD4-like molecule in parathyroid tissue

BACKGROUND Parathyroid tissue expresses the T-lymphocyte antigens CD3 and CD4, and parathyroid CD3 has earlier been proposed to interact in the regulation of parathyroid hormone (PTH) release. METHODS Anti-Leu3a, a monoclonal antibody recognizing CD4, was used to stain parathyroid tissue immunohistochemically, to influence PTH secretion from enzymatically dispersed parathyroid cells, and to immunoprecipitate parathyroid CD4. Northern blot and polymerase chain reaction were used to clarify the similarity between parathyroid and lymphocytic CD4. Serum PTH level was measured with an immunoradiometric assay in healthy control subjects and individuals with human immunodeficiency virus type 1. RESULTS The parenchyma of normal and abnormal parathyroid tissue displayed strikingly variable CD4 expression. Immunoprecipitation showed a 56 kd molecule, and Northern blot and polymerase chain reaction confirmed the similarity with lymphocyte CD4. Anti-Leu3a inhibited preferentially low calcium-stimulated secretion of PTH from dispersed parathyroid cells, without discernible influences on the cytoplasmic calcium concentration of these cells. Individuals with human immunodeficiency virus type 1 displayed significantly lower serum PTH levels than healthy control subjects. CONCLUSIONS The results suggest that the human parathyroid chief cell expresses a CD4 moiety, which seems to interact in the PTH release in vitro and in vivo and which seems to use another second messenger system than the structurally similar T-cell equivalent.

Effects of alkaline buffers on cytoplasmic pH in lymphocytes.

Objective: To study experimentally possible adverse effects of bicarbonate on cytoplasmic pH. Design: Open, randomized control trial of white blood cells from human volunteers. Setting: Experimental laboratory in a large university hospital. Subjects: Lymphocytes prepared from human blood. Interventions: The fluorescent intracellular probe 2′,7′‐bis‐(carboxyethyl)‐5,6‐carboxyfluorescein acetoxymethyl ester (BCECF‐AM) was used to study the influence on cytoplasmic pH after the addition of different alkaline buffers to lymphocytes with normal as well as decreased initial intracellular pH. Measurements and Main Results: In normal lymphocytes, sodium bicarbonate caused a marked, dose‐dependent acidification of the cytoplasm followed by a slow, often unpredictable increase. Ringers acetate solution decreased the intracellular pH dose‐dependently; this acidification effect continued throughout the measurements. In contrast, trometamol (tris) and Carbicarb® both caused a pronounced dose‐dependent and lasting alkalinization of the cytoplasm. Tris buffer mixture (Tribonate®) produced a slight initial dose‐dependent acidification, followed by a slow increase in cytoplasmic pH to values above those recorded during control measurements. Lymphocytes that were preincubated in acetate showed similar results after addition of tris buffer mixture or sodium bicarbonate. Lymphocytes with intracellular acidosis due to preincubation in an acid buffer demonstrated a more pronounced and dose‐dependent decrease of cytoplasmic pH immediately after addition of the bicarbonate‐containing buffers (sodium bicarbonate and tris buffer mixture). The decrease was only partly compensated for over the next 10 mins. Only the buffers that were not producing CO2 could fully compensate for the severe extra‐ and intracellular acidosis imposed on the lymphocytes by preincubation in an acid medium. Conclusion: Use of bicarbonate‐containing buffers often results in an initial decrease of cytoplasmic pH. (Crit Care Med 1994; 22:1550–1556)

Major histocompatibility complex class II expression and parathyroid autoantibodies in primary hyperparathyroidism

BACKGROUND Autoimmune diseases are characterized by induced parenchymal expression of major histocompatibility complex (MHC) class II antigens and circulating autoantibodies directed toward surface structures on the target cells. MHC class II expressions can be modified by viral infections of potential pathogenic importance in autoimmune reactions. Primary hyperparathyroidism exhibits incompletely clarified cause. METHODS With cryosections, human parathyroid glands were stained with monoclonal antibodies to MHC class II antigens according to a peroxidase-antiperoxidase technique. Human parathyroid adenoma tissue transplanted to nude mice and rat parathyroid glands was tested with serum from patients with hyperparathyroidism and control subjects. RESULTS Induced MHC class II expression was demonstrated on parathyroid parenchymal cells in 13 of 54 adenomatous and eight of 23 hyperplastic glands of patients with primary hyperparathyroidism. This reactivity was absent in 12 normal glands, nine normal-sized glands associated with the adenomas, and 17 enlarged glands of patients with hyperparathyroidism caused by uremia. Staining of parathyroid tissue was found with serum from 27 of 38 patients with primary hyperparathyroidism, whereas this reactivity was absent on rat thyroid and pancreatic tissue, as well as with control sera. CONCLUSION The concurrent induction of MHC class II antigen expression and c circulating antiparathyroid autoantibodies in 16 or 38 patients with primary hyperparathyroidism suggests hitherto unrecognized immunologic involvement in this disease.

Alkaline buffers for correction of metabolic acidosis during cardiopulmonary resuscitation with focus on Tribonat®—A review

A combined hypercarbic and metabolic acidosis develops during the low flow state of cardiac arrest treated with cardiopulmonary resuscitation. Several negative consequences of the acidosis have been demonstrated, two of the most important being reduced contractility of the ischaemic but still beating myocardium and impaired resuscitability of the arrested heart. Even though interventions to re-establish a spontaneous circulation should be the number one priority during cardiopulmonary resuscitation, attempts to treat the acidosis are often carried out in order to avoid the reported negative inotropic effect. Different alkaline buffers have been used, but it has been demonstrated over the years that such treatment may aggravate the situation due to a variety of deleterious side-effects of the buffers. A mixture of THAM, acetate, sodium bicarbonate and phosphate registered as Tribonat has been suggested as a suitable alternative to conventional buffer substances. The problems preceding the designation of Tribonat as well as studies evaluating its effects are reviewed in this article. Tribonat seems to offer a more well-balanced buffering without any major disadvantages compared with previously used alkaline buffers, even though improved survival has not been reported.

Tribonat--a comprehensive summary of its properties.

OBJECTIVE To review available investigations describing the properties of the buffer mixture Tribonat. DATA SOURCES Original reports published in peer-reviewed medical journals. STUDY SELECTION Review of 76 citations, including four original studies on the effect of Tribonat performed by or supervised by the author, and six original studies concerning Tribonat originating from the institution to which the author is affiliated. DATA EXTRACTION Computer search of the literature regarding treatment with alkaline buffers during cardiopulmonary resuscitation. DATA SYNTHESIS Routine buffering of acidosis has been questioned, but clinical situations still exist where such treatment is regarded as indicated. In such cases, a buffer with advantageous qualities and few side-effects is desirable. The hitherto commonly used buffers do not always fulfill these requirements, and a more profound knowledge of the alternative Tribonat may therefore be warranted. CONCLUSIONS The reviewed articles support the assumption that Tribonat may offer important advantages over previously used buffers in situations where administration of an alkalinizing agent is indicated.

Improvement in histological diagnosis of primary hyperparathyroidism with a monoclonal antiparathyroid antibody

The monoclonal antiparathyroid antibody E11 reacts with a glycoprotein of high molecular weight, which acts as a calcium receptor on the surface of parathyroid cells and mediates calcium regulation of parathyroid hormone (PTH) release. Reduced expression of the calcium receptor has been implicated as a cause of the defect in PTH regulation in the pathological parathyroid parenchyma of patients with hyperparathyroidism (HPT). The present study evaluated the efficacy of immunostainings with the E11 antibody in comparison with routine histopathological methods including staining by the oil red O technique for histological discrimination between normal and pathological parathyroid glands. Parathyroid tissue from euparathyroid individuals invariably presented intense and homogeneous surface staining, with the antibody on virtually all chief cells, while the pathological glands from patients with HPT consistently showed heterogeneous and reduced immunostaining. Even minimally enlarged pathological glands from individuals with mild hypercalcemia and the normal-sized glands associated with adenomas displayed parathyroid chief cells with reduced antibody reactivity. The monoclonal antiparathyroid antibody should constitute a useful tool in parathyroid histopathology not only by its ability to identify the parathyroid tissue, but also by directly demonstrating the functionally normal and abnormal cells within the parathyroid tissue.

Effect of tris buffer on free cytosolic calcium in myocardial cells

OBJECTIVE To study the effect of tris buffer on free cytosolic calcium in vitro. DESIGN Open, randomized, control trial of dispersed rat myocardial cells. SETTING Experimental laboratory in a large university hospital. SUBJECTS Dispersed myocardial cells from Sprague-Dawley rats. INTERVENTIONS The influences of pure trometamol (tris) and a tris butter mixture, as well as conventional sodium bicarbonate on free cytosolic calcium in suspended rat myocardial cells were studied with the fluorescent intracellular probe fura-2. MEASUREMENTS AND MAIN RESULTS Addition of pure trometamol (tris) resulted in a significant increase of free cytosolic calcium in myocardial cells suspended in a buffer containing 1.25 mM of ionized calcium. The actions of trometamol display a dose-dependency in relation to the concentration of external ionized calcium since the ionized calcium response was reduced in a buffer with 0.5 mM of extracellular ionized calcium. Furthermore, removal of external ionized calcium totally prevented trometamol induced increases of ionized calcium, indicating that this increase is dependent on transmembrane ionized calcium fluxes. When tris buffer mixture was investigated in 1.25 mM of calcium, as well as 0.5 mM of external ionized calcium, a decrease of ionized calcium was noted initially, followed by an increase during the observation period. Addition of sodium bicarbonate to the two experimental settings resulted in a more prominent initial decrease of ionized calcium, followed by a slower increase which did not reach the initial values during the 20-min observation period. Extracellular pH was also included as a variable. When the cells were suspended in a buffer containing 1.25 mM of ionized calcium with a pH of 6.80 instead of 7.40 (as above), addition of pure trometamol also resulted in an increase of ionized calcium; however, after 20 mins this increase was smaller as compared with the results above. When tris buffer mixture as well as sodium bicarbonate was added, initial decreases of ionized calcium were recorded, followed by smaller increases during the observation period, compared with the increase in buffers with a pH of 7.40. CONCLUSIONS Pure trometamol (tris) induces an increase in free cytosolic calcium in suspended myocardial cells.

Immunohistochemicaf evidence of parathyroid hormone—related protein in human parathyroid tissue

Immunohistochemical staining for parathyroid hormone-related protein (PTHrp) was investigated on cryosections of 17 normal-sized human parathyroid glands, 47 adenomatous and hyperplastic glands of hypercalcemic patients with primary or uremic hyperparathyroidism, and 5 metastases of parathyroid carcinoma. Utilizing a polyclonal antiserum recognizing aminoterminal PTHrp, approximately two-thirds of the normal and enlarged glands but none of the parathyroid carcinomas demonstrated a conspicuous immunostaining. The extent and intensity of the reactivity varied between the glands even of individual patients. The staining was found in chief and oxyphilic parathyroid cells, and studies of cell suspensions substantiated that the immunoreaction was present also on the surface of the parathyroid cells. Reduced PTHrp expression in the functionally more dedifferentiated parathyroid tissue was suggested by comparison of the normal (i.e., suppressed) and adenomatous parathyroid tissue from the individual patients and by parallel stainings with the monoclonal El1 antibody, which recognizes a calcium sensor involved in the regulation of parathyroid hormone release. The findings substantiate a functional role for PTHrp in euparathyroid and hyperparathyroid individuals.